Spark-plug.



SPARK PLUG.

APrjyQAUON FILED 11111124. 1913` Patented 00115, 1915 x ALBERT SCIMIDT,OF FLINT, MICHIGAN, ASSGNGR TO UNITED STATES PATENT operon.

onnivrrron renrrron coureur,

0F FLINT, MIOHIGAN,=A CORPORATION F MICHIGAN.

SPARK-PLUG.

Specification of Letters Patent.

Patented lot.. 5, itali.

Application filed July 24, 1913. n Serialo. 780,565.

useful Improvements in Spark-Plugs, of

which the' following is a specifica-tion, reference being had thereintothe accompanying drawings.

The invention relates to spark plugs, and

lhas more particular reference to the means for securing the insulatorsin the.' metallic casing.

In the drawings: Figure l is'va central longitudinal section through theplug; and Fig. 2 is a perspective view of some of the parts detached. l

A isa metallic casing provided `with a hexagonal portion B and threadednipple C.

D is a bushing having a threadedengagement with an internally threadedportion of the casing A," and being provided with a tapering or conicalbore.

E is an insulator formed with a shoulder F for bearing against acomplementary shoulder G upon opposite sidesv of said shoulder anupwardly-tapering portion H and a downwardly extending portion I ofreduced diameter.

It is one of the objects of the invention to provide means for holdingthe insulator within the casing by a bearing 'of considerable ext-ent.Such a bearing performs the double function oi distributing the stressupon the insulator and also of forming a heat conducting medium forabsorbing the heat of the insulator and dissipating the saine. To thisend the tapered bore of the bushing D ispreferably complementary to thetapering portion ofthe insulator. Instead, however, of forming a directengagement between the bushing and insulator, an inner bushing- J islirst sleeved'upon the insulator, this being preferably made of n softermetal than the bushing D and forming a bearing surface on the insulator.Preterably I form the bushing` of aluminum.

vthe burning gases, will be conducted in the casing and also having rhismetal' is sufficiently soft and pliable and also possesses a high degreeof heat conductivity.

In assembling the parts, the insulator E is placed in the casing A, witha gasket or packing K interposed between the shoulders F and G. Thebushing upon the tapering portion' oft the insulator,

4after which the bushing D is engaged therewith and turned in thethreaded portion of the casing A. This will draw the bushing J downwardupon the insulator, and at the same time will press the shoulder Ftoward the shoulder G, compressing the gasket and forming a gas tightseal. By reason or' the extended surface of the bushing the pressure onthe insulator is distributed and is comparatively slight at any onepoint, while at the same time this extended surface rapidly absorbs theheat of the insulator and conducts it into the bushing D and casing A.As a result, the heat absorbed by the inner end of the insulator, whichis in contact with through the portion I of reduced diameter, enlargedportion, and from the latter be' dissipated through the bushing and wallof the casing.

IVhat I claim as'my invention is:

l. A spark plug, comprising an outer casing havinga threaded nipple, aninternally threaded outer portion and a shoulder bearing therebetween,an insulator having a p0rtion Within vvthe nipple portion and an.enlargement fornnng a shoulder opposed to the shoulder on the casingand a portion tapering outward from said shoulder, a

bushin0F havinff a threaded en `a ement with J is then sleeved into thel the internally threaded portion of said casy' ing and a tapered bore,andan inner sleeve or bushing of substantially the length of said lastmentioned bushing interposed between said last mentioned bushing and thetapering portion of said insulator forming an extended surface incontact with each and f ka heat conducting medium therebetween.

2. A spark plug, comprising a casing, an insulator therein having anenlargement formhg a shoulder opposed to n eomplerst-mentioned taperingbushingr to `form .1 10 nlentmy Shoulder on the casing, and tapersentand heabconducting medium.

ing' olitwud from Suid shoulder, n tapering In testimony whereof I affixmy signature bushing surrounding said tapering portion in presence oftwo Witnesses.

of the 1115111211101' und hmjn? :L tllr'eaded en- ALBERT SCHMIDTgagement wlth the casmg, una :L second l tapering bushing ext-endingsubstantaly the Witnesses:

length of said 'i'sn1entio11ed tapering bush- B. DYNIUUARD,

ing, interposed between Suid insulator and "V. Gr. LA ROCK.

